1. Field of the Invention
This invention relates to inductor type dynamoelectric machines, e.g., motors, generators and, more specifically, to a support and positioning structure for a stator assembly thereof.
2. Background Art
Dynamoelectric machines are commonly used as motors for converting electrical to mechanical energy. Inductor type dynamoelectric motors may be used as adjustable speed drives for high speed operation. However, such dynamoelectric machines may also be used for electrical generation by mechanically driving the rotor by an external source thereby generating electrical energy in the armature windings. Such dynamoelectric machines are generally characterized by a stator which includes both AC armature and DC exitation coils surrounding a coilless rotor. In this type of dynamoelectric machine, there are no rotating field winding or armature coils, slip rings, brushes and associated connections which are common to machines having rotating windings. Since dynamoelectric machines contain fewer rotating parts they have a more solid rotor construction and are particularly suitable for high speed application. One version of such an inductor type dynamoelectric machine, employs a circumferentially distributed arrangement of C-shaped armature elements surrounding a generally cylindrical field coil which in turn encloses a transverse pole magnetic rotor. U.S. Pat. Nos. 437,501 and 2,519,097 and 3,912,958 describe earlier machines of this type of design.
A more recent version of such an inductor type machine is disclosed in commonly owned U.S. Pat. No. 4,786,834 and No. 4,864,176. A spool-like support structure supporting field windings and armature elements is disclosed therein. The spool-like structure is made of a nonmagnetic material and has a hollow, elongated central portion extending concentrically about a longitudinal axis. This central portion supports a field coil and defines an interior longitudinal passageway for accommodating a coaxial rotor inserted therethrough. End portions are located at each end of the central portion and extend radially outward therefrom. Each of the end portions is preferably provided with radially oriented grooves in its axially outermost surface. The grooves are configured to receive and orient legs of generally C-shaped armature coil elements arranged in a circumferentially distributed pattern about the periphery of the spool-like structure. The end portions of the spool-like structure are axially spaced and radially dimensioned and the grooves in the outer face of each portion are angularly spaced so as to precisely position the armature elements in three orthogonal directions. The spool-like structure is also provided with ports within which cooling fluid is pumped by the rotor.
A stator mounting arrangement is disclosed in U.S. Pat. No. 5,006,748 which teaches the use of mounting supports which are affixed to the dynamoelectric machine housing. The end portions of the stator assembly are fastened to the mounting supports thereby mounting the stator assembly within the housing.
Other features, advantages and benefits of these dynamoelectric machines, including the stator support structures thereof, are described in detail in U.S. Pat. Nos. 4,786,834; 4,864,176 and 5,006,748. Each of these patents is incorporated herein by reference and made a part of this disclosure.
Particularly in high power, high rotation dynamoelectric machines, use of the spool-like stator support structures has not significantly reduced thermal resistance and minimized losses in armature flux leakage. Also, with such high speed operation, additional support for the stator assembly may be desireable, particularly at the radially outer portions of the C-shaped armature elements. It is therefore desirable to provide a mechanical support for the stator assembly which may be mounted externally to C-core elements to maintain the structural integrity of the stator assembly, particularly at the radially outer portion of the armature elements.
It is also desireable to provide a support structure which will allow air gap tolerances within the machine to be reduced and, reduce thermal resistance within the machine thereby improving its efficiency and performance. Moreover, it is also desirable to minimize eddy losses and armature flux leakage within these dynamoelectric machines.
It is therefore an object of the present invention to provide support for the stator package making it a self-standing structure.
It is also an object of the present invention to provide structural means to attach the stator package to the machine frame.
It is also an object of the present invention to simplify and facilitate the motor assembly and construction.
It is also an object of the present invention to reduce stator and motor vibration levels, by providing a stiffer stator package.
It is also an object of the present invention to provide a low thermal impedance path for the machine heat, hence facilitating external cooling, and reducing hot spots inside of the machine.
It is also an object of the present invention to provide additional cooling means close to the machine core, if a cooling fluid is circulated inside the supporting ring.
It is also an object of the present invention to provide self-centering of the stator and rotor members, allowing close tolerances for the airgap.
It is also an object of the present invention to control and reduce armature leakage fluxes, maintaining stray losses low.